Differential timing device mechanism



United States Patent.

DIFFERENTIAL TllVIING DEVICE MECHANISM Edwin R. Smith, Seneca Falls, andConstantine F. Cafolla, Waterloo, N.Y., assignors to Seneca FallsMachine Chempany, Seneca Falls, N.Y., a corporation of Massac usettsApplication September 4, 1957, Serial No. 682,057

1 Claim. (Cl. 74-689) such feeding operations or other machine functionsmay be controlled.

It is the general object of this invention to provide improved mechanismby which the angular movement of the timing drum will be at all timescoordinated with the linear movement of the tool carriage, when eithersingly or jointly operated and controlled.

To the attainment of these objects, we utilize a differential connectionbetween the drum and the primary and the secondary means for feeding themoving member or tool carriage.

The single figure of the drawing is a diagrammatic plan view, partly insection, of the driving mechanism adapted to the stated purposes of thisinvention.

Referring to the accompanying drawing, a tool carriage 10 rotatablysupports a gear nut 11 threaded on a lead screw 12. The screw 12 isnormally held stationary by a magnetic friction brake 14. The gear nut11 is revolved by a meshing gear 15, also rotatably supported on thecarriage 10. The gear 15 is slidable on a rotated splined shaft 16.Rotation of the gear 15 by the shaft 16 rotates the gear nut 11 on thestationary lead screw 12, and causes the nut 11 to be moved axially ofthe lead screw and to move the tool carriage 10 along with it.

The shaft 16 may rotate the lead screw 12 through sprockets 20 and 21and a chain 22. The sprocket 20 is driven from the shaft 16 through amagnetic clutch 23. When the clutch 23 is activated, the screw 12 willbe rotated by the shaft 16, and the gear nut 11 thus receives anadditional axial movement, providing a differential in crease in therate of tool carriage travel. Suitable control means determines thatwhen the clutch 23 is to be closed, the brake 14 will be automaticallyreleased.

The shaft 16 will be normally and continuously rotated by a gear 27 fromany suitable source of power.

A control or timing drum 30 is to be turned angularly in eitherdirection in predetermined relation to the rotation of the feed shaft 16and lead screw 12.

The drum 30 has a Worm gear 31 continuously rotated by a worm 32 on aworm shaft 33. The shaft 33 is mounted in bearings 35 and 36 and has anoffset arm 37 on which a planet pinion 38 is freely rotatable.

A sun gear 49 is mounted on a drive shaft 41 which is rotatably mountedfor timed rotation by the splined shaft 16 through sprockets 42 and 43and a chain 44.

The planet pinion 38 also meshes with internal gear teeth 59 on adifferential casing 51, which in turn is loosely mounted on the driveshatt 41. The casing 51 is driven by sprockets 54 and 55 and a chain 56from the lead screw 12.

As has been previously explained, the normal linear movement of the toolcarriage 10 is effected by turning the gear nut 11 on the normally fixedlead screw 12. Such rotation of the gear nut 11 is also communicated tothe sun gear 40 through the sprockets 42 and 43 and chain 44. i

The differential casing 51 is normally held from rotation by the brake14, and the sun gear 40 rotates the arm 37 and worm 32 to turn the wormgear 31 and timing drum 30 at a proportional but much reduced speed.

For faster carriage travel, the lead screw 12 is itself rotated byclosing the magnetic clutch 23 and by simultaneously opening themagnetic clutch 14, thus imparting an additional and bodily axialmovement to the nut 11 and carriage 10. Such rotation of the lead screw12 also acts through the sprockets 54 and 55 and chain 56 to rotate thecasing 51 and to thus superpose additional rotational speed on the drum30 to correspond to the increased tool carriage travel.

The rotation of the drum 30 is thus at all times coordinated with thetravel of the carriage Ill, and this proportional relation betweenlinear travel and angular displacement is maintained unchanged bychanges in either the speed or the direction of carriage travel.

Contact pins 60in one or more series may be selectively mounted in thedrum 30 and may activate any usual limit switches to effect desiredchanges in speed or direction of carriage travel, or other machinefunctions.

It is to be understood that the magnetic brake 14 will be releasedwhenever the magnetic clutch 23 is activated, and vice-versa.

Any suitable provision may be made for selective control. of the brakesand switches in accordance with tool carriage travel. One sucharrangement is shown in the patent to Dinsmore and Smith #2,714,324issued August 2, 1955.

Having thus described our invention and the advantages thereof, we donot wish to be limited to the details herein disclosed, otherwise thanas set forth in the claim, but what we claim is:

In a machine tool having a tool carriage, in combination, anormally-stationary and axially-fixed lead screw, a gear nut mounted onsaid carriage and having its nut portion threaded on said lead screw,normally-operated means to rotate said nut 'on said normally-fixed leadscrew to shift said tool carriage bodily axially of said normallyfixedlead screw in said machine tool, a drum rotated in predeterminedrelation to the axial movement of said tool carriage, and driving meansfor said drum comprising a three-part differential gear means having anouter but internally-toothed driven gear, an inner but externallytootheddriving gear, and an interposed gear mounted on a bearing portion of acrank arm and connecting said gears, an operating connection from onepart of said differential gear means to said lead screw, and anoperating connection from a second part of said differential gear meansto the means for rotating the gear nut, whereby rotation of the controldrum is made responsive to any and all axial movements of said toolcarriage.

References Cited in the file of this patent UNITED STATES PATENTS1,283,386 Wenzelmann on. 29,1918 2,144,735 Granberg et a1. Jan. 24, 19392,359,255 Smith Sept. 26, 1944 OTHER REFERENCES Ser. No. 309,100, Robinet al. (A.P.C.), published May 4, 1943.

